WASHINGTON (AP) — The U.S. population is projected to grow by 15 million people in 30 years, a smaller estimate than in prior years, the Congressional Budget Office said Wednesday. The CBO projected the population will rise from 349 million people this year to 364 million people in 30 years, a 2.2% smaller gain than it predicted in 2025.
The budget office attributed the slower growth to President Donald Trump’s hard-line immigration policies and an expected lower fertility rate. The CBO said the country’s total population is projected to stop growing in 2056 and remain roughly the same size as in the previous year.
In its projection, the CBO said the population would begin to shrink in 2030 if immigration were removed, as deaths would start to exceed births. The report said that under such a scenario, immigrants would become an increasingly important source of population growth.
The CBO also said Social Security and Medicare, which it described as already under strain from an aging population, would face increasing pressure as even fewer people are expected to be in the labor force paying taxes. It projected that by the end of the decade, all baby boomers born between 1946 and 1964 would be over age 65.
William Frey, a demographer at the Brookings Institution, said the shift would still matter even if Trump-era immigration limits and increased deportations ended sooner than the CBO’s full period. “it’s still a demographic shock,” Frey said.
Frey said lower fertility would also affect the population outlook over the four-year window of the second Trump administration. “that reduces the number of kids who are going to be born in that four-year period,” he said.
The CBO’s new projection comes as Trump has pushed for the largest mass deportation campaign in history, according to the report. The CBO’s numbers account for the success of those efforts in the first year of his second term in office, the AP said.
In September, the CBO issued a revised demographics report saying Trump’s plans for mass deportations and other strict immigration measures would result in roughly 320,000 people removed from the United States over the next 10 years. The AP reported that the administration has used a range of methods to remove people, including a visa ban on applications from some countries and deploying Immigration and Customs Enforcement agents in U.S. cities to track down immigrants in the country illegally.
The article said Trump’s tax and spending law, passed by Congress and signed in July, included roughly $150 billion to ramp up his deportation agenda over the next four years. The AP said that funding included money for extending the U.S.-Mexico border wall, building detention centers and adding thousands of law enforcement staff.
Beyond immigration policy, the report focused on fertility and the pace of population replacement. For the U.S. generation to replace itself without immigration, the fertility rate would need to be 2.1 births per woman, the AP reported. The article said the fertility rate was expected to be 1.58 in 2026 and projected to drop to 1.53 in 2036, where it is projected to remain over the next two decades.
The CBO’s outlook also relied on data about immigration levels that can vary quickly from year to year. The article said immigration has fueled U.S. population growth this decade partly because of an aging population and fertility below the replacement rate, and that immigration is a “wild card” in such estimates because it varies much more year to year than births and deaths.
The AP reported that the U.S. Census Bureau said immigration increased the U.S. population by 2.8 million people in 2024 over the previous year. It also reported that the Current Population Survey estimated the number of adult immigrants fell by 1.8 million people from January to November 2025, while some experts said those figures could reflect reduced immigrant participation in the survey rather than a sharp drop in immigrant numbers.
The article said the CBO reduced its immigration estimate for 2025 by 1.6 million people in September, and that Wednesday it said the U.S. added 410,000 immigrants last year. It projected immigration would gradually increase through 2030 and then grow more slowly through 2036 before jumping to an average of 1.2 million people a year from 2037 to 2056, the CBO said.
Kenneth Johnson, a senior demographer at the University of New Hampshire, said in an email that the arrival of immigrants also affects the population outlook through potential childbearing in the near term. “These immigrants bring both themselves and the potential for children in the near term,” Johnson said. He added that immigrants “contribute both to the labor force through their arrival but also to the potential future growth of the US population through their potential to have children in the near term.”